Your conjecture is correct -- we are currently not distributing amd64 binaries, but you should be able to download the package sources and rebuild them.  That said, it may be easier to install 32-bit compatibility libraries and run using those (although I'm not sure exactly which libraries are needed).

The build environment for the Ubuntu packages was just a regular 32-bit Ubuntu 9.04 box with the build dependencies listed in the control files installed.  The RPMs have been tested to work on amd64, but the Ubuntu packages have not.  They should -- the architecture is abstracted in the build scripts in all the necessary locations.

You need an existing binary installation of GT.M at /tmp/gtm.  You can download a binary install from http://sourceforge.net/projects/fis-gtm/

GT.M databases are architecture specific, but that specificity depends on the endianness of the architecture.  Since 32- and 64-bit GT.M on x86 GNU/Linux are the same endian-ness, the same database files can be used by both.  However, at any given instant in time, a database file can only be open by one GT.M installation.

Global directories and object files are not the same between 32- and 64-bit GT.M.

The main benefit to 64-bit GT.M is that object files can be placed in shared libraries by the standard Linux ld utility.  So, when you get into the many hundreds and thousands of concurrent users, memory is used more efficiently.

The main benefit to 32-bit GT.M is that it will run on both 32- and 64-bit Linux installations.

Regards

-- Bhaskar